Perception and sanitisation of human faeces for soil fertility management in Uganda

Abstract:

Soil fertility decline in sub-Saharan Africa stems from a number of causes, among which is nutrient drain through unregulated crop harvests, soil erosion and leaching deep into the soil profiles. Yet nutrient replenishment in cropping systems in the region remains a myth due to prohibitive mineral fertiliser prices and lack of skills among small-scale farmers for appropriate fertiliser use and benefit. On the other hand, human faeces, particularly the type produced from the urine-diversion dry toilets, code named, EcoSan toilets variously located in urban parts of the country remains untapped. Although human faeces have been used in other countries for soil fertility improvement, in Uganda, the extent of use and attitudes of farmers towards accepting it as a soil management input are yet to be established. As such, a study comprising of a socio-economic survey and a field experiment was conducted in Mukono and Wakiso districts in central Uganda. The survey aimed at establishing the level of use and attitudes of farming communities towards human faeces from Eco-San toilets for soil fertility improvement at small-scale farmer level. The survey was carried out using a semi-structured questionnaire which was administered to 80 households, 20 of these were Eco-San toilet users and 60 were randomly selected among the non users of Eco-San toilet. It emerged that only 19% of the respondents used faecal materials for soil fertility management. This was largely in Wakiso district where a non-Governmental cultural organisation known as Buganda Cultural Development Foundation (BUCADEFF) launched an aggressive promotion for community utilisation of the material. Eighty three percent of the respondents expressed interest in using the material for soil fertility improvement as long as they were sure of safety from diseases. In fact lack of knowledge of safe handling and clarification of the agricultural value of the material (59%) featured prominently among the reasons for the nonuse of the faeces by the farming communities. A field experiment was carried out at the Makerere University Agricultural Research Institute at Kabanyolo, in Wakiso district to evaluate the extent to which compost sanitisation could be achieved when the human faeces are blended with a spectrum of other forms of agricultural residues. The composting experiment comprised five treatments, namely, sole human faeces (HF), sole poultry litter (PL), sole cattle manure (CM), 50% HF + 50% CM and 50% HF + 50% PL. These treatment combinations were allocated to air-tube wooden composting structures of 1 m x 1 m x 1 m in a randomised complete block design, in three replications. During composting, the materials within the structures were moistened using tap water up to 50% moisture content in order to create optimum condition for the decomposer microbial activity. The materials were composted for a period of 90 days when most of them showed evidence of maturity. Temperature reading was taken during the process of decomposition. Blending faecal materials with cattle manure or poultry litter led to temperature rises, and effective sanitisation (p<0.05) of the compost. Overall, faecal material alone generated the lowest temperatures (24 oC), while faeces + poultry litter registered the highest temperature (53 oC) on day 8. In terms of germination index, faeces + poultry litter or cattle manure registered the highest GI values of 63 and 53%, respectively, way beyond the 50% known to be the minimum requirement for phytotoxicity reduction. Sole human faeces registered the highest electrical conductivity (EC) value (9.63 Sm cm-1) among the treatments, meaning it was highly saline. With regard to nutrient content, sole human faeces had the lowest concentrations of nitrogen, phosphorus and organic carbon, but maintained a high level of total K. Its pH was also high compared to others. On the other hand, poultry litter registered the highest (p<0.05) concentrations of nitrogen and phosphorus; but the lowest pH among the treatments. In terms of phytotoxicity reduction using animal wastes, the blend HF + CM attained a 75%, while HF + PL registered 100% success in eliminating both Enterrococus and E. coli species. Human faeces alone registered lethal counts of E. coli (>102 c.f.u./gramme) throughout the composting period. The Findings established that farmers were willing to use human faeces for soil fertility management, especially in their blended forms. Compost matured within 45 days, with poultry litter performing above other faecal based composting materials in terms of sanitising human faeces and having high nutrients concentration. The study also revealed that sensitisation of farmers was needed to improve acceptance.

Description:

A thesis submitted in partial fulfillment of the requirements for the award of the Masters of Science Degree in Soil Science of Makerere University.